node js = (google chrome's engine created in c++) V8 engine + javascript repper code

• install node js for your os
• check the installation if err
• get basic understanding of npm "nahi pta mujhe"
• create new node js file with the command

npm init

npm init -y

• understand how to read out the docs go to nodejs.org/docs
• be familiar with moduls like

//  file system, http, many more;

const fs = require("fs");

• you can write/create a file

fs.writeFile("filename.ext","data",callback(err));

callback for handle error in between the process.

• appending text to the file

fs.appandFile("filename.ext","data",callback(err));

• rename file

fs.rename("filename.ext","newNameToFile",callback(err));

• copy file

fs.copyFile("firstfilenameOrPath","secondfilenameOrPath",callback(err));

Data of first file will be copied into the second file if everything heppn correctly or it will show specific error message.

• deleting a file

fs.unlink("filename.ext",callback(err));

• deleting an empty directory (we can use "rm" or "rmdir")

fs.rm("directorypath",callback(err));

• deleting a directory with files (we can use "rm" or "rmdir")

fs.rm("directorypath",{recursive:true},callback(err));

this recursive is an optional argument, which is importent for delete the directory with files.

const http = require('http');

• creating server with the help of HTTP module of node js

//server via http method ✅
const http = require('http');
http.createServer((req,res)=>{
  res.writeHead(200,{content_type:"plane/text"});
  res.end("hello sir ... server is created by traditional http method");
}).listen(3000,()=>{
  console.log('on http://localhost:3000/');
})

• installing npm packeges

npm install packegename

or we can only use i to indicate install keyword

• uninstalling npm packeges

npm uninstall packegename

• installing particular version for specific packege

npm i packegename@version

whenever  you install any packege for particular work, it will install another required packeges for proper functioning of that packege into node module folder as well.

• Dependencies : are these packeges & another required packeges for proper functioning of the application.

• Devdependencies : are those packeges, which are used in development phase only.

• create a server with express in an easy way then http method

// server via express method ✅

const express = require("express")
const app = express()
app.get("/",(req,res)=>{
  res.send("hello sir.. server is created by express")
}).listen(3000,()=>{
  console.log("check on http://localhost:3000");
})